The Other House

She wants to go home while sitting in her own living room, or believes there is a second, identical house she also owns. This has a name and a mechanism, and arguing is not advised.

What is actually happening?

Two systems that normally agree have stopped agreeing. She recognizes the house and does not feel that it is hers, so the mind resolves the contradiction by proposing a copy.

Recognition is not one process. There is the part that identifies a place — this is a kitchen, this layout, that window — and there is the part that supplies the feeling of familiarity, the sense of mine.

Normally those arrive together. When the second one fails, the person gets an accurate identification with no accompanying feeling of belonging. That is a genuine contradiction, and the explanation that resolves it is that this must be a different one. A copy. A replica somewhere else. She is not reasoning badly; she is reasoning correctly from information that is wrong.

This is why it sits in the same family as Capgras delusion, where a spouse is believed to have been replaced by an identical impostor. Places, people, same underlying failure.

How common is it?

Much more common than most families are told. Roughly a third in moderate Alzheimer's.

Reported prevalence is as high as 30% in the moderate stages of Alzheimer's disease and around 20% in dementia with Lewy bodies.

Which means that if she believes there is a second house, she is one of a very large group, and you are not looking at something rare or ominous. Most families never hear the term because nobody thinks to name it.

Is this what "I want to go home" means?

Very often, yes — and it explains why taking her home does not settle it.

The most common form of this is the person who asks to go home while they are already in the house they have lived in for forty years. Families drive them around the block and return, and it does not help, and everyone concludes she is more confused than they thought.

She is not asking for a location. She is reporting that this place does not feel like hers, and "home" is the only available word for the feeling that is missing.

Which is why home is often not a building at all. It can be a childhood house, a time of life, or a state of feeling safe and useful and among her own people. Something that has genuinely gone.

• Ask what home is like rather than explaining where she is. "Tell me about your kitchen there." It often produces a conversation instead of a standoff.
• Treat it as an emotional report. Unsettled, unsafe, out of place, wanting something familiar.
• Watch the clock. If it clusters in the late afternoon, treat it as part of that pattern — light, tiredness and hunger all feed it.
• Try the practical things first. Food, the bathroom, a warmer room, less noise. A surprising share of this resolves with a snack.

What do we say about the other house?

Not that it does not exist. Go around the belief rather than through it.

Direct contradiction fails reliably here, and the failure is expensive: you become the person who argues, and she becomes someone who has to defend herself in her own living room.

• Do not confirm it either. Elaborate agreement builds a story you will have to maintain, and it can escalate into planning to sell or move to the other house.
• Be non-committal and move on. "I am not sure about that one. Come and look at the garden with me."
• Defer rather than refuse. "We can't do anything about that today" outperforms "there is no other house."
• Answer the practical worry underneath. Often it is about money, security or possessions. "Everything is looked after" is what she is actually asking about.
• If she wants to go there, agree it is not today. Coats on and a walk around the block sometimes settles it; sometimes the plan itself is enough.
• Warn the family. A relative who cheerfully argues the point, once, in front of her, can undo weeks of a calm approach.

When should we get it looked at?

When it appears suddenly, when it comes with other new symptoms, or when it is frightening her.

Most of the time this is a slow feature of the illness and needs no intervention beyond a change of approach. Three exceptions:

• Sudden onset. Abrupt misidentification, especially with drowsiness, agitation or a change over hours to days, points at delirium — usually infection, dehydration, pain or medication. That is urgent.
• With new neurological signs. Weakness, speech change, facial droop. That is an emergency call, not a symptom to manage.
• When it is causing real distress or risk. If she is frightened in her own home, trying to leave at night, or making financial decisions about a house that does not exist, it needs clinical attention.

On medication: there are case reports of misidentification delusions resolving with a low-dose antipsychotic, and in a person in genuine distress that conversation is legitimate. It is also true that these drugs carry serious risks in dementia including stroke and death, and that people with Lewy body dementia can react severely. Non-drug approaches first, a clear look for a physical cause, and a specific target agreed before starting anything.